I have a 2006 GXP and when you put it in drive it shifts to park then back again. The door locks go up and down and you can feel the trans shifting back and fourth. On the heads up display the D and P flick back and fourth, the speedo is bouncing. In neutral it does and in manual there are no control of the paddle shift. I tried grounding the TCM, the ECM. Put two more ground straps to the engine. I’m thing it’s either the TCM or the shift control module which is unfortunately in the transmission. Any ideas?
